Features of heat and mass exchange in laminar flows of micro and nanofluids in tubes and channels

In recent years, high efficiency of using suspensions of nanoparticles for cooling of the operating systems compared to a homogeneous liquid has been shown, and the parameters of suspensions effective for various specific devices have been selected in experiments. A brief review of the relevant experimental data, as well as mathematical models of the flow of micro- and nanofluids, based on the incompressible Navier-Stokes equations with boundary conditions accounting for tangential momentum transfer of the particles and temperature jump due to diffuse reflection at rough walls, are presented. For the case of a laminar flow between infinite parallel plates with constant heat fluxes through the plates, an analytical solution is obtained for the velocity and temperature fields. Numerical calculations showed that with an increase in the momentum transfer coefficients at the plates, the flow accelerates significantly, which contributes to an increase in volumetric flow with the same pressure drop across the channel due to a decrease in the shear stress at the wall. Correspondingly, the heat transfer through the plates and the heat removal with the fluid flow increase. Based on the obtained analytical relationships, it is possible to select the parameters of the plate surfaces in such a way as to optimize the system, for example, to reduce the energy loss due to viscous and thermal dissipation or to obtain uniform temperature distributions in the liquid with asymmetric heat flows through the plates.Key words: microfluidic, nanofluidics, heat and mass transfer, laminar flows. Pages of the article in the issue: 62-67Language of the article: UkrainianIn recent years, high efficiency of using suspensions of nanoparticles for cooling of the operating systems compared to a homogeneous liquid has been shown, and the parameters of suspensions effective for various specific devices have been selected in experiments. A brief review of the relevant experimental data, as well as mathematical models of the flow of micro- and nanofluids, based on the incompressible Navier-Stokes equations with boundary conditions accounting for tangential momentum transfer of the particles and temperature jump due to diffuse reflection at rough walls, are presented. For the case of a laminar flow between infinite parallel plates with constant heat fluxes through the plates, an analytical solution is obtained for the velocity and temperature fields. Numerical calculations showed that with an increase in the momentum transfer coefficients at the plates, the flow accelerates significantly, which contributes to an increase in volumetric flow with the same pressure drop across the channel due to a decrease in the shear stress at the wall. Correspondingly, the heat transfer through the plates and the heat removal with the fluid flow increase. Based on the obtained analytical relationships, it is possible to select the parameters of the plate surfaces in such a way as to optimize the system, for example, to reduce the energy loss due to viscous and thermal dissipation or to obtain uniform temperature distributions in the liquid with asymmetric heat flows through the plates.Key words: microfluidic, nanofluidics, heat and mass transfer, laminar flows.Pages of the article in the issue: 62 - 67Language of the article: Ukrainia